Business & Industry
Feb 29, 2016
Biomass: zero carbon energy
Biomass is non-fossil fuel material of biological origin constituting a renewable energy source. Common biomass fuel sources are wood, municipal waste and alcohol fuels. Because of its availability throughout the world, woody biomass is explored as a source of energy.
Energy from Woody Biomass
The majority of the paper manufacturing industry in the U.S. uses self-generated and renewable energy for paper manufacturing. Most of the mills that use self-generated energy are "integrated mills", which are mills generally defined as those that produce pulp and paper on-site. A non-integrated mill is generally defined as a mill that purchases their pulp and usually does not have access to self-generated energy, most commonly derived as a by-product of the pulping process. Non-integrated mills have the choice of off-setting carbon emissions or purchasing renewable energy to power their manufacturing process.
Paper mills that are able to use biomass can reduce the need to purchase energy off the grid, which is often generated by burning fossil fuels. In some cases, the use of biomass has allowed paper mills to operate with net-zero carbon emissions when their forests are replanted depending on the calculation method.
The forest products industry is the leading producer and user of biomass energy and produces more energy from biomass than all the energy produced from solar, wind, and geothermal sources combined.
Biomass and Carbon Neutrality
The Intergovernmental Panel on Climate Change (IPCC) currently considers biomass emissions to be carbon neutral. The IPCC views biomass emissions as part of the natural carbon balance (called biogenic carbon which has been part of the Earth's biosphere for millennia) and states that such emissions do not add to atmospheric concentrations of carbon dioxide. The Energy Information Administration (EIA) 1605(b) reporting instructions contain a footnote citing the IPCC guidance and stating that "reporters may wish to use an emission factor of zero for wood, wood waste, and other biomass fuels."
Energy-rich biomass carbon – derived from wood chips, bark, sawdust and pulping liquors recovered from the harvesting and manufacturing processes – is atmospheric carbon dioxide that is transformed and sequestered by trees during their growth. When these biomass fuels are burned, the emitted CO2 is in fact the atmospheric carbon dioxide that has been sequestered during growth, and it becomes part of the natural carbon cycle that includes trees, air and other normal CO2 emissions. This cycle is a closed-loop: new tree growth keeps absorbing atmospheric carbon dioxide; hence, there is no net contribution to the atmospheric CO2 level.
Burning Woody Biomass for Fuel
The pulp and paper manufacturing supply chain is complicated – and similar to many aspects of the paper life cycle – the answer is never a simple "yes" or "no". Regarding biomass for energy, there are studies that question how the impacts of the use of biomass on carbon storage in ecosystems is measured.
There are two basic approaches to carbon measurements and balances. First, basic measures of non-biogenic (fossil based) carbon discharges from all human activities like burning fuels, decomposition of wastes in landfill and industrial processes. This is basically the simple accounting approach that the IPCC is driving globally whereby emitters just measure their fossil fuel carbon emissions. Second, measuring all carbon discharges (biogenic and non-biogenic), all carbon uptake, and the change in carbon storage levels. This approach is an inventory of carbon stores that looks at how much is being added by use of fuels (including biomass) and how much is being removed through sequestration into the trees, oceans and soil.
There are several environmental groups that challenge the notion of whether biomass should be considered carbon neutral. According to a report by the Environmental Paper Network (EPN); "The question of carbon neutrality in forest ecosystems or plantations needs to be explored on different levels, including the landscape level and the forest or plantation stand level. We are seeking to understand how our many specific activities and decisions regarding how many trees to harvest and at what intervals ultimately will lead to landscape level changes if they are widely employed."